Although not our top choice for to-do apps iOS or Mac, OmniFocus lost out largely to its competition. It's a great app that's often overlooked due to its cost. If that's why you passed it up, then today is your lucky day: OmniFocus for Mac and iPad are 50% off. That's still means you're paying $40 and $20, respectively, but it's a major discount. If you're on a Mac and/or iPad and into the GTD method, this deal is definitely worth considering.